(Istituto di Scienze Marine – CNR – Napoli, Italy)
High resolution geophysical survey in transition zone
Coastal and transitional areas represent highly dynamic, quickly-changing environments. These areas are subject to multiple interactions with the marine-land-fluvial systems processes. Different types of processes such as coastal erosion, seawater intrusion, pollution and transport of sediment affect these areas. The geophysical surveys permit to improve the understanding of these phenomena and consequently to assess the vulnerability and the potential of the coastal zone. The development of geophysical models integrated into management coastal system is the key to achieve reliable prediction model. Moreover, coastal areas are among the most populated and urbanized areas. For these reasons, the application of geophysical minimally invasive methods, such as seismic, geoelectric techniques and electromagnetic survey, are the most appropriate tool to provide geology and to collect data on land-sea zone.
This study reports several examples of coastal and marine geophysical surveys. In particular, in coastal areas, the seismic reflection/refraction survey plays a key role to increase the knowledge of civil engineers. Seismic survey provides information on subsoil geometry and evaluate the hydraulic and mechanical characteristics necessary in the planning, design and construction stages. We utilize a not standard approach to acquire seismic data in the backshore-foreshore area, joining up land and marine seismic data, using a marine streamer connected to a land cable. This method allows to obtain a seismic site characterization in terms of primary wave velocities and shear wave velocities (both the P-wave and S-wave velocities are used to define the elastic modules and geotechnical parameters). We also show other coastal/marine geophysical studies such as 2D/3D Electrical Resistivity Tomography (ERT) and magnetometry survey.